A comparative study of the electrical characteristics and device instabilities in InGaZnO thin-film transistors (IGZO-TFTs) with four different high-k gate dielectrics (Al2O3, HfO2, Ta2O5, and ZrO2) has been conducted. High-k gate dielectrics have a sufficiently low leakage current for the gate insulator of IGZO-TFTs and ZrO2 has the highest dielectric constant, followed by Ta2O5, HfO2, and Al2O3. However, the charge trapping in high-k gate dielectrics induced the bias stress instability and degradation of IGZO-TFTs over time. In particular, the positive bias stress (PBS) and positive bias temperature stress (PBTS) caused a large positive threshold voltage (V th) variation due to electron trapping, while the negative bias stress (NBS) and negative bias temperature stress (NBTS) brought about a much smaller V th shift. In particular, the Al2O3 and HfO2 gate insulators have significant threshold voltage shifts for the PBS and PBTS measurements. Among the four different high-k gate dielectrics, ZrO2 is the most promising high-k gate dielectric for the IGZO-TFTs because of its high dielectric constant, low subthreshold swing, high mobility, large drive current, small hysteresis, and high on/off current ratio.

We performed high spectral resolution observations of Mercury's exosphere on 2005 October 30 and 31 using the European Southern Observatory-New Technology Telescope, La Silla, Chile. The large spectral range, 385-855 nm, of the spectrograph, ESO Multi-Mode Instrument, provides a unique opportunity to search for nonidentified species in Hermian's environment. In this paper, we report a tentative detection of atomic aluminum in the exosphere of Mercury. This detection should be confirmed by further observations and can be used as an upper limit for this element in Mercury's exosphere. We also estimate the upper limit for the column densities of Fe and Si exospheric atoms. Detection of Al, a refractory element, if confirmed, as well as its high exospheric abundance (between 2 and 18) with respect to Ca would suggest either an unexpected surface composition or a relation between exosphere and surface composition that is not well understood.

The analysis of modulation-broadened experimental magnetic resonance spectra by the fitting of theoretical lineshape functions is described together with tests on zero field NMR lineshapes from 69Co in cubic cobalt. It is shown that for small modulation amplitudes values for the resonance width, intensity and mode admixture may be obtained. For large modulation amplitudes considerable errors may occur in the deduced values of intensity and width but their ratio, the resonance amplitude, is still accurately determinable. The application of correction curves to spectral parameters of resolved lines is summarized.

Charge trapping and tunneling characteristics of silicon-nitride (Si3N4) layer with various thicknesses were investigated for applications of tunnel barrier engineered nonvolatile memory (NVM). A critical thickness of Si3N4 layer for suppressing the charge trapping and enhancing the tunneling sensitivity of tunnel barrier were developed. Also, the charge trap centroid and charge trap density were extracted by constant current stress method. As a result, the optimization of Si3N4 thickness considerably improved the performances of NVM.

The single-transistor dynamic random-access memory (1T-DRAM) using a polycrystalline-silicon thin-film transistor (poly-Si TFT) was investigated. A 100-nm amorphous silicon thin film was deposited onto a 200-nm oxidized silicon wafer via low-pressure chemical vapor deposition (LPCVD), and the amorphous silicon layer was crystallized via eximer laser annealing (ELA) with a KrF source of 248 nm wavelength and 400 mJ/cm2 power. The fabricated capacitor less 1T-DRAM on the poly-Si TFT was evaluated via impact ionization and gate-induced drain leakage (GIDL) current programming. The device showed a clear memory margin between the "1" and "0" states, and as the channel length decreased, a floating body effect which induces a kink effect increases with high mobility. Furthermore, the GIDL current programming showed improved memory properties compared to the impact ionization method. Although the sensing margins and retention times in both program methods are commercially insufficient, it was confirmed the feasibility of the application of 1T-DRAM operation to TFTs.